1. Field of the Invention
The present invention relates to a funnel for a color CRT, and more particularly, to a funnel for a color CRT that is capable of reducing a deflection power as well as a leakage magnetic field by modifying a structure of a yoke portion in which a deflection yoke is mounted.
2. Description of the Background Art
FIG. 1 is a partially cut side view showing an internal construction of a color CRT, and FIG. 2 is a sectional view taken along line Axe2x80x94A of FIG. 1, showing a structure of a yoke portion of a funnel of the color CRT in accordance with a conventional art.
With reference to FIG. 1, As shown in FIG. 1, a color CRT is formed with its external appearance by a panel 10 coated with a red, green and blue color fluorescent material 11 on the inner face thereof, and a funnel 20 sealed at the rear side of the panel 10 and maintaining an internal pressure in a high vacuum state.
A shadow mask 40 serving for color selection is mounted at the inner side of the panel 10 through the medium of a frame 30.
An inner shield 60 for shielding a magnetic field such as an earth magnetic field so that an electron beam (B) injected from an electron gun 80 is not influenced by the magnetic field is mounted at a rear side of the frame 30.
Especially, the funnel 20 includes a body portion 21 coupled to the panel 10, a neck portion 23 into which the electron gun 80 is installed, and a yoke portion 25 in a cone shape formed between the body portion 21 and the neck portion 23.
A deflection yoke 50 for deflecting the electron beam (B) injected from the electron gun 80 to the entire fluorescent surface 11 is mounted at the yoke portion 25.
In the color CRT, as the electron beam (B) irradiated from the electron gun 80 is deflected in the horizontal and the vertical direction by a static magnetic field of the deflection yoke 50, it collides with the fluorescent surface 11 formed at the inner surface of the panel 10, radiating the fluorescent material, so that an image is reproduced.
A cut-out section of the yoke portion 25 of the funnel 20 is typically formed to have a circular structure. But, in this respect, in order to reduce a power consumption of the deflection yoke 50, the maximum power consumption source, as shown in FIG. 3, a yoke portion 25xe2x80x2 of a funnel 20xe2x80x2 is formed to have a non-circular structure.
As a measure for minimizing the deflection power of the color CRT, the yoke portion 25xe2x80x2 of the funnel 20xe2x80x2 is designed in the following range.
With reference to FIGS. 4 and 5, on the assumption that a long axis length of the outer face of the yoke portion 25xe2x80x2 is xe2x80x98Hxe2x80x99, a short axis length of the outer face of the yoke portion 25xe2x80x2 is xe2x80x98Vxe2x80x99, a diagonal length of the outer face of the yoke portion 25xe2x80x2 is xe2x80x98Lxe2x80x99, xcex94H=Lxe2x88x92H, xcex94V=Lxe2x88x92V, xcex94HV=xcex94H+xcex94V, the yoke portion is designed in the range of 0.3 less than xcex94HV/L less than 0.6.
However, the conventional designing range of the yoke portion is designed to be optimized in a color CRT of which screen ratio is 4:3, it is hardly optimized to be adoptable to a high definition television having a screen ratio of 16:9.
In other words, reduction of a power consumption in the deflection yoke, the maximum power consumption source, of the typical color CRT is a critical matter. In this respect, however, in order to improve a luminance of the fluorescent material of the color CRT, an anode voltage for accelerating the electron beam should be resultantly increased, it is difficult to reduce the power consumption of the deflection yoke.
Especailly, in case of a color CRT having the screen ratio of 16:9 such as the HDTV, a higher deflection force than that of the CRT having the screen ratio of 4:3, and at this time, the deflection frequency should be raised, causing problems that a deflection power is increased and a deflection magnetic field is readily leaked outside the CRT because of the deflection force caused due to the high frequency.
In addition, in line with the strengthened regulation for the leakage magnetic field, a compensation coil is additionally installed to reduce the leakage magnetic field, which, however, makes the structure of the color CRT more complicate and increases the power consumption.
As a result, the designing range of the yoke portion 25xe2x80x2 in accordance with the convention is not suitable to the color CRT having the screen ratio of 16:9.
Therefore, an object of the present invention is to provide a funnel for a color CRT that is capable of reducing a deflection power and a leakage magnetic field while satisfying a high luminance or a high frequency by optimizing a design range of a yoke portion in case that a screen ratio is about 16:9.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a color CRT of which a funnel has a body portion coupled to a panel, a neck portion in which an electron gun is installed and a yoke portion connecting the body portion and the neck portion and having a deflection mounted therein, wherein the outer face of the yoke portion satisfies a relational expression of 0.6 less than xcex94HV/L less than 0.71, of which xe2x80x98Lxe2x80x99 indicates a diagonal length of an outer face of the yoke portion, xe2x80x98Hxe2x80x99 indicates a long axis length of the outer face of the yoke portion, xe2x80x98Vxe2x80x99 indicates a short axis length of the outer face of the yoke portion, xcex94H indicates a difference between the diagonal length xe2x80x98Lxe2x80x99 and the long axis length xe2x80x98Hxe2x80x99, xcex94V indicates a difference between the diagonal length xe2x80x98Lxe2x80x99 and the short axis length xe2x80x98Vxe2x80x99, xcex94HV indicates the sum of xcex94H and xcex94V.
In the funnel of a color CRT of the present invention, the outer face of the yoke portion satisfies a relational expression of 0.64 less than xcex94HV/L less than 0.71.
In the funnel of a color CRT of the present invention, the yoke portion is formed in an about square shape, and the corner portion is thicker than both side portions and upper and lower portions.
In the funnel of a color CRT of the present invention, a sectional area from a reference line to the outer face of the yoke portion is 900xcx9c1200 mm2.
To achieve the above objects, there is also provided a color CRT having a body portion coupled to a panel, a neck portion in which an electron gun is installed and a yoke portion formed to be connected between the body portion and the neck portion and in which a deflection coil is mounted, wherein the yoke portion satisfies a relational expression of 0.6 less than xcex94Hxe2x80x2Vxe2x80x2/Lxe2x80x2 less than 0.71, of which xe2x80x98Lxe2x80x2xe2x80x99 indicates a diagonal length of an inner face of the yoke portion, xe2x80x98Hxe2x80x2xe2x80x99 indicates a long axis length of the inner face of the yoke portion, xe2x80x98Vxe2x80x2xe2x80x99 indicates a short axis length of the inner face of the yoke portion, xcex94Hxe2x80x2 indicates a difference between the diagonal length xe2x80x98Lxe2x80x2xe2x80x99 and the long axis length xe2x80x98Hxe2x80x2xe2x80x99, xcex94Vxe2x80x2 indicates a difference between the diagonal length xe2x80x98Lxe2x80x2xe2x80x99 and the short axis length xe2x80x98Vxe2x80x2xe2x80x99, xcex94Hxe2x80x2Vxe2x80x2 indicates the sum of xcex94Hxe2x80x2 and xcex94Vxe2x80x2.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.